Vodka can be made anywhere in the world and of any raw material. What makes a vodka, is its Distillation strength.
Processing
While any raw material can be used to produce a vodka, there are some that are commonly associated with premium-quality vodka. They are Grains (particularly barley, wheat, and rye) and potatoes.
Fermentation
Once a sugary liquid is made, Fermentation takes place.
Distillation
Vodka is a Diluted Neutral Spirit.
Post-distillation
These spirits are Unaged, reduced to Bottling Strength. Typically 40% ABV